Design optimization of autoswitch hydrogen absorption and desorption device using metal hydrides

Metal hydride is an influential and promising material for hydrogen utilization. Researchers have carried out a large number of studies on hydrogen storage apparatus, and developed a few new devices for its promotion. Unfortunately, for most metal hydride reactors, the hydrogenation and dehydrogenation are two independent processes owing to the different required conditions, which could cause many inconveniences and safety problems to the H₂ absorption & desorption cycle with high frequency and intensity. Hence we proposed a new type of autoswitch H₂ absorption & desorption device based on the structure improvement, which consists of rotation disc, fixed disc and the reactor. The numerical simulation for H₂ absorption/desorption using LaNi₅ was accomplished, and the optimizations on both structure and operation conditions were achieved within a certain period of cycle time. Simulation results show when the single cycle time is set to 1600?s, the absorption temperature has to be lower than 45?°C (3?MPa) and pressure higher than 1.28?MPa (20?°C), and the desorption temperature should be higher than 41?°C (0.1?MPa) and pressure lower than 0.48?MPa (80?°C) under the same cycle time. Meanwhile, the effects of reaction finish time, operating temperature and H₂ pressure during absorption/desorption process was investigated and simulation data were also fitted to develop the structural optimization. Under the hydrogenation/dehydrogenation conditions of 3?MPa (20?°C)/0.1?MPa (80?°C), the simulation results indicate the optimal initial reacted fraction and total cycle time are 0.07 and 1287?s, respectively. Moreover, both structures of autoswitch device with 4 and 6 openings have been optimized to satisfy the requirement of each stage. The autoswitch H₂ absorption & desorption device can realize the automatic switch between hydrogenation and dehydrogenation orderly and controllably, which would provide convenience for the occasions with this demand and show its remarkable value during popularization and application.